Axial type reciprocating engine



All@ 23, 1955 J. M. TowLER ETAL 2,715,875

XIAL TYPE RECIPROCATING ENGINE Filed oct. 21, 1949 s sheets-sheet 1 35 In uentors John maurice wler Frank Hathom Towler El 6"""1 @iwf/@s AUS. 23, 1955 J. M. TowLx-:R ET AL 2,715,875

AXIAL TYPE RECIPROCATING ENGINE Filed Oct. 2l, 1949 3 Sheets-Sheet 2 Aug. 23 1955 J. M. TowLER ET AL 2,715,875

AXIAL TYPE RECIPROCATING ENGINE Filed oct. 21, 1949 :s sheets-sheet s Inventors John maurice Towler Frank Hathorn Towler E13/m, MyW/x /f/y United States Patent O AXIAL TYPE RECIPRoCATrNG ENGINE John Maurice Towler, Carleton in Craven, Skipton, and

Frank Hathorn Towler, Dob Park, near Otley, England, assignors to Electraulic Presses Limited, Radley, England, a corporation of the Kingdom of England Application October 21, 1949, Serial No. 122,698

Claims priority, application Great Britain October 26, 1948 12 Claims. (Cl. 10S- 173) This invention relates to hydraulic multi-ram pumps of the kind having a cylinder block in which the pump rams are disposed around a common axis the rams being reciprocated either directly or through push rods without the inter-position of connecting rods by means of a ram actuating device comprising a wobbler which is given angular oscillation in two planes in relation to the axes of the rams by means of a swash member. The above description is to be read as a definition of the term of the type specied used in the claims at the end of this specification. It is to be understood that if a pump or compressor of the above type is supplied with pressure fluid hereinafter referred to as liquid and provided with suitable valve gear it will also operate as a rotary engine or motor. Accordingly the term pump hereinafter used in this specification is to be read as including a motor as well as a compressor.

One of the objects of the present invention is to provide a pump of the above type which has improved means for taking the thrust loads on the wobbler and the swash member which will not crush under the heaviest loads the pump is likely to be subjected to. of the invention is to improve generally the eiciency of such pumps.

ln an axial ram pump according to the present invention the axial load on the wobbler and on the swash member is taken by bearings consisting of opposed plane and relatively rotatable surfaces which are held out of metal to metal contact by an interposed film of oil. Each said bearing may comprise a washer one of which is disposed between the wobbler and the inclined face of the swash member and the other between the rear face of the swash member and a supporting member or reaction plate, with said washers secured against rotation relative to the swash member, one of the co-acting surfaces of each bearing being composed of a relatively soft bearing metal and one of said surfaces vin each bearing being formed with radial grooves which are open at their inner ends to a space in which is available, during use, a continuous supply of oil.

Where washers are used the soft surfaces are on the outside faces of the assembled washers so as in one case to contact the rear face of the wobbler and in the other case the opposing face of the reaction plate or supporting surface for the swash member. Where no washers are used the soft metal surfaces may be applied to the wobbler and the supporting member for the swash member respectively, with the faces of the swash member of hard metal. Alternatively the two faces of the swash member may be of the soft metal when the co-acting faces of the wobbler and the supporting member will be of hard metal. ln the preferred construction, both the wobbler and the swash member are given freedom to tilt in relation to their supporting surfaces and one manner of obtaining this effect will be explained in the following description of the example illustrated in the accompanying drawings in which:

Patented Aug. 23, 1955 Fig. l is a longitudinal section through an axial ram pump embodying the features of the present invention.

Fig. 2 is a view of the same pump in elevation with a small part broken away to expose a feature which is hereinafter referred to.

Fig. 3 is a transverse sectional view taken in a plane substantially on the line 3--3 of Fig. 1.

Fig. 4 is a fragmentary sectional view taken in a plane substantially on the line 4 4 of Fig. 3.

Figs. 5, 6 and 7 are transverse sectional views respectively taken in planes substantially on the lines 5 5, 6*(5 and 7-7 of Fig. 1.

The axial ram pump illustrated in the drawings comprises a driving shaft 1, a swash member 2 that is a press it on the driving shaft, a wobbler 3 mounted on a nose or extension 4 of the swash member, a reaction plate 5 for supporting the swash member against the axial load, a crank case 6 enclosing the swash mechanism, a pump body 7 containing axially disposed rams 8 and 9 with their valves, and a simple gear pump 10 functioning as a booster and driven by a flexible extension 11 of the driving shaft 1.

In the pump illustrated the thrust on the wobbler and the thrust on the swash member are taken by bearings comprising a washer 12 disposed between the wobbler n and the inclined face of the swash member and a further v in the swash member.

A further object washer 13 disposed between the rear face of the swash memberand the opposing'face of the reaction plate 5. These washers are held against rotation in relation to the swash member by dowel pins 14 which t in holes These washers, on the sides which oppose the wobbler and the reaction plate respectively, are faced with a covering of a relatively soft bearing metal 13b and such soft facings are traversed by radial grooves 13a for the distribution of oil as shown in Fig. 4. We have found that it is an advantage that these radial grooves shall'have sharp edges 13C to avoid taper lead at the leading edge of each bearing sector.

Oil is caused to circulate to the bearing surfaces by being first drawn inwards through radial holes 15 in the reaction plate 5 into an annular space 16 between the reaction plate and rear boss 2a on the swash member. From this annular space 16 some of the oil passes up the radial grooves in the face of the washer 13 and the remaining oil flows through a series of axial holes 17 into the grooves in the opposing face of the other washer 12. Owing to the angularity of the forward face of the swash member some of these holes 17 will open into the grooves part way along their length whilst others, of these holes will open into an annular space 18 at the centre of the washer 12. The oil in the space 18 is free to find its way between the wobbler 3 and a bush 19 on the nose 4 of the swash member.

In the pump illustrated the pump bores are divided into two sets with the bores of one set spaced alternately with the bores of the other set, and the area of one set being less than, preferably half, the area of the other set. This arrangement has as one of its features the disposing of the delivery valve bores in planes normal to the axis of the pump shaft with the delivery bores associated with one set of rams disposed in a plane which is nearer to the swash member than is the plane in which are disposed the delivery bores associated with the other set of pump bores. The separate delivery passages for each set of pump bores are also disposed in different planes, those, for example, associated with the bores of smaller area being disposed nearer to the swash member than those associated with the bores of greater area or vice-versa.

According to a preferred arangement six ram bores and rams are provided in two sets of three, for rams 8 and 9 respectively, with all six of the delivery valve bores 20l being parallel to each other and grouped on the opposite. sides. of the pump body. The delivery boresV in each group are staggered, for example two 8a being associated with. one set of pump bores and one 9a with the other set at. one. side of' thev body as shown, in' Fig. 2;. the. delivery passages (not shown) being arranged so as to unite two delivery bores. on one side of the purnp'body with the one: ofthe same seti onv the other side of the pump body and to connect allthreeawith they deli-very main.V

In the improved .pump ofthe. presentV invention, a` novel; construction and arrangement of linlet valve guides and suction passagesl isV used, this. consisting' in forming; in the end of the pump body opposite to that housing therams, a singley cylindrical cavityr 21 concentric with; the pump driving shaft and into this cavity is pressed; an annular bush 221 to. as to l'eave a. gap or space 23 between the end of the bush andthe bottom of the cavity with.y part of the bush projecting. out ofthe pump body to` form an annular spigot. Concentric with. the pump bores and suction valve bores: a corresponding. number of parallelV bores are formed; in the bush and these constitute the suction valve guides. The suction passages may conveniently be formed by providing holes in the bush between the guide bores leading to the space` 23 between the end of the bush and the corresponding bore 21- iny the pump body.

lnthe above construction the end. of the pump body is closed by means of a cover plate 24 which locates on the projecting portionl of the suction. valve guide and is itself provided with an annular portion 25 which projects through a hole in the centre of the aforesaid annular suction valveA guideA bush 22 thusV forming the inlet manifold 25av and makes a joint at 26 with the pump body 7. The'cover plate may conveniently form a part of the gear typeY boost pumpy and the extension 11 of thev main drivingshaft for driving this pump can. pass through` thew above mentioned annular projecting portion 25 of the cover.

TheV bores 27 which incorporate the delivery valve seats are cylindrical and terminate at their inner ends; in frusto-conical portions 28, which themselves terminate in lcylindrical passages 29', thev junctions between the frusto-conical portions and the cylindrical passagesrforrn-l ing the delivery valve seats.

Each delivery valve guide 30 hasv a short cylindrical portion at its outer endwhich registers in the above mentioned cylindrical bore 27, a long reduced portion 31 and a short frusto-conical portion 32 which registers with the outer end of the frusto-conical portion of' the' delivery valve bore. This portion has slots formed in it to provide passages for the oil.

Each delivery valve consistsof a short frusta-conical' portion 33V and a long cylindrical portion 34 of av smaller diameter, the said cylindricalV portion being guided in a corresponding cylindrical hole inthe delivery valve guide 30. A compressionV spring is also housed in the delivery valve guide and presses on the end of the cylindrical portion of the delivery valve. The included angle of the anks ofthe frusto-conical portion of the deliveryl valve is preferably slightly less than the included angle. of the anks of the `frustoconical portion of the delivery valve bore so that the delivery valve seats onV the junction between the inner end of the frusto-conical portion 28 of the delivery valve bore and the cylindriealpassage.

Surplus oil froml the boost pump passes4 througbf a constricted orifice 35, see Fig. 2, into the crank case tov cool the lubricating oil and back again. to'- thereservoir'. orifice 35 is such that, provided that there isV an adequate supply of surplus oil` to cool the crank case, there will be suiiicient pressure to force theV oil through'l the suction valves into the pump chambers and force the pump rams againstV the face of the wobbler; On the other hand'. if the gear pump is starved of oil, or if for 4 any reason the gear pump fails to provide an adequate supply of oi1 the flow of oil through the orifice into the crank case will be so reduced as to reduce the back pressure to such an extent that the oil will no longer be forced into the pump chambers and therefore the pump will cease to pump. This. is a safeguard because it ensures that the bearing members in the crank case will not be loaded, (and they cannot be loaded' if the pump is not pumping), unless there is an adequate surplus of oil. to coolY the. crank case.

`In orderto prevent contamination of the lubricating oll with that carried in from the boost pumpa thin annular metal ring 36 is interposed between the lubricating oil and the cooling oil so that the crank case 6 is divided into. a central chamber 37, containing the parts of the ram actuating device and the lubricating oil, and a surrounding annular chamber 38 containing the cooling oil. This thin annular dividing ring or screen consists. for preference of perforated sheet metal supporting extremely fine gauze. l

A further annular screen 39 of large mesh isprovided inside the fine screen 36 to prevent the oil Within thechamber 37 from swirling, which would interfere withk the inwardV flow of. oil to the radial holes-15 in the reae# tion `plate 5. y

The oil within the central chamber 37 is replenished by that. which leaks pastthe pump plungers, and although. this leakage is minute, it is suflcient to renew the oil. within the screen with reasonable frequency during the operationv of the pump thereby maintaining its lubricating quality.

As previously mentioned in this. specification theV wob.- bler 3 is free to tiltA in relation to the swash member 2. Similarly the swash-` member is also permitted a small amount of tilt in relation. toA the reaction plate 5 and, this is brought about by forming the main driving shaft so: that the extension 11 isl free to ileX and supporting the main; shaft 1 against the radial load by means of a single journal bearing 40. The bearings in both cases, are thussimilar in elect to. each other as the. wobbler is also.v supported against the radial load by a comparatively short journal bearing constituted by the bush 19, a loose t betweeen the twovkgiving to the Wobbler the desired freedom to tilt. i

The ram. endsf may be either spherical or conical but a quasiconical form is preferred withl the anks of the quasi-conical surface curve to a large radius. in: such a: manner that underA full load. the area of contact on the ram end spreads. nearly tothe-two ends of the quasi-cone. In'a typical case: with a ram diameter of. one half inch, aworking; pressure. of 7,000 p. s. i. an angle of tilt of 12 of the swash: member and the radius of the curved. ank of thel quasi-cone 6"l the departure. of the. quasi-cone from. the true.- was of the order off0.00l". y

I'he drivingshaft 1 and swash, member 2. rotates,`

whereas the pump. body 7 is stationary, but the. wobbler. 3- isrnade to `rotatervery slowly in a reverse direction to the driving shaft by means of bevel gearing. one gear wheel 41.V

n the plungers being free to rotate. This geared wobbler in. combination with film-lubricated thrust-washers enables the pump. to be operated continuously at very highpressures withoutappreciable wear but the invention is not limited; to aA pumpzhaving this gear.

The. two delivery manifoldsv 43- and 44- are in communication with; a. combined unloading-relief valve not Shown which. is so arranged that, when a predetermined pressure. is, reached. the. largerY plungers are. unloaded or,I in; other wordsfr the: delivery manifold' 44 is by-passed to inlet, and pressure 1s maintained in delivery manifold 43 by a non-return valve. Finally, when the maximum pressure is reached, the delivery cf the small plungers along manifold 43 blows olf at the relief valve.

The combined unloading-relief valve can be arranged to operate as a sustained pressure valve, in which case there is only a diierence of 200 to 300 p. s. i. between the predetermined pressure at which the large plungers are unloaded or by-passed and the maximum pressure at which pressure is sustained with the delivery of the small plungers blowing olf at the relief valve. Alternatively, the valve may be arranged to operate the pump as a twostage high pressure pump, in which case there is a difference of 2009 or 3G00 p. s. i. between the predetermined pressure at which the large plungers are unloaded or bypassed and the maximum pressure at which the small plungers blow oli at the relief valve. Furthermore, the booster pump 10 may be increased in capacity, thereby providing low pressure for the rapid approach stroke of a press ram, with the addition of sustained pressure or twostage high pressure for the pressing operation, as described above.

The unloading-relief valve may be adjustable so that the maximum blow-oli pressure may be varied at will to suit the pressing operation.

We claim:

l. An axial ram pump of the type described comprising, in combination, a body having a plurality of parallel pump cylinders annularly arranged at equal radii about a central axis, a plurality of pump plungers slidably reciprocable in said cylinders of the annular series, said cylinders being alternately relatively large and small in diameter, power operated means for reciprocating said plungers in progressive overlapping timed sequence each with an intake stroke in one direction and a pressure stroke in the reverse direction in each cycle, a fluid supply manifold, inlet valve means for admitting fluid from said manifold to each cylinder in the course of the intake stroke of the associated plunger, a pair of uid delivery manifolds in said pump body extending generally transversely of each of said cylinders and spaced apart axially of the cylinders, and discharge valve means individual to each cylinder and operative in the course of the pressure stroke of the asscciated piston to deliver pressure liuid to a particular one of said delivery manifolds.

2. A pump according to claim l in which said power operated means comprises a device having a working face relatively inclined to a plane normal to said axis and located in opposed separable operative contact with the outer ends of said plungers, power drive means for electing a relative gyratory rocking motion between said face and said body, and means including a driving member on the pump body cooperating with a driven member carried by said device for effecting a relative rotational displacement between said face and said body.

3. A pump according to claim l in which the discharge valve means for the small cylinders comprises individual valves located in one common plane transverse to the axis, and for the large cylinders comprises individual valves located in another common plane transverse to said axis and located at a greater distance along said axis than said rst mentioned common plane from said power operated means.

4. A pump according to claim 3 in which the small cylinders are the same in number as the large cylinders, and the respective individual discharge valves have valve bores extending transversely of the axis, the valve bores for one-half of the small and large cylinders extending in closely-spaced parallel laterally-staggered relation to one side of the pump body, and the valve bores for the other one-half of said cylinders extending similarly to the opposite side of the pump body.

5. An axial ram pump of the type described comprising, in combination, a body having a plurality of parallel pump cylinders annularly arranged about a central axis, a

plurality of pump plungers slidably reciprocable in said cylinders, power operated means for reciprocating said plungers in progressive overlapping timed sequence each with an intake stroke in one direction and a pressure Stroke in the reverse direction in each cycle, a uid supply manifold, inlet valve means to admit fluid from said manifold to each cylinder in the course of the intake stroke of the associated plunger, and discharge valve means to permit delivery of fluid from each cylinder in the course of the pressure stroke of the associated piston, said power operated means comprising a power drive shaft aligned with said axis, an annular stationary abutment member encircling said shaft and presenting a iirst bearing face, a swash plate rotatable with said shaft and having on the side remote from said member an active ace inclined to a plane normal to said axis, and a flat annular washer interposed in operative bearing assembly between said member and swash plate and secured for rotation with said swash plate and having a second bearing face in bearing engagement with said iirst bearing face,

a wobbler plate coacting with said inclined face and in bearing engagement with the outer ends of said plungers to eiect reciprocation of said plungers upon rotation of said shaft.

6. An axial ram pump of the type described comprising, in combination, a body having a plurality of parallel pump cylinders annularly arranged about a central axis, a plurality of pump plungers slidably reciprocable in said cylinders, power operated means for reciprocating said plungers in progressive overlapping timed sequence each with an intake stroke in one direction and a pressure stroke in the reverse direction in each cycle, a fluid supply manifold, inlet valve means to admit iluid from said manifold to each cylinder in the course of the intake stroke of the associated plunger, and discharge valve means to permit delivery of fluid from each cylinder in the course of the pressure stroke of the associated piston, said power operated means comprising a power drive shaft aligned with said axis, an annular stationary abutment member encircling said shaft and presenting a rst bearing face, a swash plate rotatable with said shaft and having on the side remote from said member an active face inclined to a plane normal to said axis, and a flat annular washer interposed in operative bearing assembly between said member and swash plate and secured for rotation with said swash plate and having a second bearing face in bearing engagement with said rst bearing face, an annular wobbler plate encircling said axis and having a third bearing face on one side in opposed relation to said inclined face, and having an active face on the other side in bearing engagement with the outer ends of said plungers to eect reciprocation of said plungers, a at annular washer interposed in operative bearing assembly between said swash plate and wobbler and secured for rotation with said swash plate and having a fourth bearing face in bearing engagement with said third bearing face, and means for positively constraining said wobbler plate to elect relative rotation between said swash plate and wobbler plate upon rotation of the former by said shaft.

7. A pump according to claim 6 in which one of said rst and second bearing faces is formed with a plurality of narrow generally radial grooves extending from the inner periphery to the outer periphery of said first mentioned washer, and having means for supplying lubricant to said grooves.

8. A pump according to claim 7 in which the sides of said grooves have sharp marginal edges in the plane of bearing face in which they are formed, thereby avoiding taper lead.

9. A pump according to claim 7 in which the bearing face with the grooves is formed of relatively soft metal and the other bearing face is formed of relatively hard metal.

l0. A pump according to claim 6 in which one of said .7. Ist and second bearing faces and one of said third and fourth bearing faces are each formedv with a plurality' of` generally radialgroovesA extending from the inner periphery to the outer periphery of` the associated washer, and: havingmeans for supplying lubricant to said grooves.

11. An axial ram pump of the type described comprising, in combination, a body having a plurality of parallel pump cylinders annularly arranged about a central axis, a plurality of pump plungers slidably reciprocable inv saidL cylinders, power Voperated means for reciprocating said" plungers in progressive overlapping timed sequence each' with an intake stroke in one direction and a pressure stroke in the reverse directionV inv each cycle, a iiuid supply manifold in said pump body, passages in the pump body forV supplying iluid` to said manifold, inlet valve means. to admit iluid from said' manifold to each cylinder in the course ofthe intake stroke of the associated plunger, discharge valve means' to deliver uid from each cylinder in the course of the pressureY stroke of' the associated' piston, said plungers being separable from said power operated means and being held operatively against said power operated means'when the pump is operating by the fluid' pressure of the uid' received in the cylinder from' said manifold, said'power operated means having coopera'- tive. relatively movable bearing surfaces and lubricantconducting passages opening thereto, a lubricating' oil containing chamber enclosing said poweroperated means, andv means including passages in theV pump body forV directing uid from said manifold around said chamber for cooling lubricating oil within said chamber.

l2. A pump according to claim ll in which the last mentioned means comprises a iiow` passage vfrom said manifold to said'chamber, and arestrictedl orifice in said ow passage effective to buildup a back pressure in saidI manifold upon 'a predetermined'rate of fluid' flow therethrough, whereby anv inade'quatejow'for cooling purposes throughsaid orifice vvi'll` result inA a reduced pressure in said manifold inadequate to maintain said plungers in operative association with said' power operatedv means.

Reiki-encesk Cited in thele ofV this patent UNITED STATES PATENTS 1,971,601 Dilg Aug. 28, 1934 2,131,857 Lauret Oct. 4,` 1933V 2,238,252 Davis Apr. 15, 1941: 2,270,263 Butlerl Iuly 20 1942 2,385,990 Huber Oct. 2,. 1.945 2,433,222 Huber Dec. 23, 11947 2,454,563 Mercier Nov. 23,V 1.948 2,461,279 Huber Feb. 8, 1949,v 2,495,685 Beaman et al Ian. 31 1950 2,520,632 Grcenhut Aug. 29, 1.950k

FOREIGN PATENTSv 165,539 Switzerland 1934` 588,614 Great Britain 1947 912,421 France 1946 

